Decompression valve



Sept. 15, 1959 J. M. TOWLER 2,904,074

DECOMPRESSION VALVE 'Filed Feb. 20, 1956 v v INVENTOR JOHN MAURICETOWLER C A @FRANK-HATHORN "FOWLER, EXECUTOR BY JZQM WH/ ATTOR EYSDECOMPRESSION VALVE John Maurice Towler, deceased, late of Mayfair,London, England, by Frank Hathorn Towler, executor, Dob Park, Otley,England, assignor to Electraulic Presses Limited, Rodley, England, alimited-liability company of Great Britain Application February 20,1956, Serial No. 566,658

Claims priority, application Great Britain February 25, 1955 '6 Claims.(Cl. 137-63015) This invention relates to decompression or exhaustvalves of the kind which for example are used to release the compressedenergy of the liquid in a hydraulic press cylinder prior to opening theprefill-exhaust valve for the return stroke of the press ram.

One object of this invention is to provide a decompression valve ofsimple and improved construction such that the compressed energy may bereleased in 'a fraction of a second without causing serious shock orpressure surge in the associated hydraulic system. A further object ofthis invention is to provide a decompression valve so constructed thatthe compressed energy may be released at a controlled rate.

Broadly the present invention consists in a decompression or exhaustvalve for releasing the compressed energy in a hydraulic cylinder, forexample the cylinder of a hydraulic press, said valve having a valvemember which is movable axially in relation to a series of passages thearrangement being such that as the valve moves it first opens an exhaustport and then uncovers in turn the series of passages to permit thecompressed liquid in the hydraulic cylinder to have access to the openexhaust port at a controlled rate for the purpose of preventing a toorapid release and serious shock or pressure surge in the hydraulicsystem.

One embodiment of this invention comprises a decompression valve for ahydraulic press consisting of a mushroom type valve opening into thepress cylinder and so constructed and arranged that the head of the saidvalve is surrounded by a cylindrical shroud having a number of radialpassages throughout its length so that, as the valve opens, the saidpassages are uncovered by the valve head consecutively therebycontrolling the rate of access of compressed liquid in the presscylinder to the annular passage uncovered by the said valve. It will beunderstood that the said valve may be moved axially a distanceequivalent to about half the diameter of the valve seat and the saidvalve movement may be effected by means of an actuating cylinder orother suitable means.

In order that the invention may be clearly understood a decompressionvalve according to the above embodiment will now be described by way ofexample, by aid of the accompanying drawing which shows the same invertical section mounted concentrically in the head of theprefill-exhaust valve of the hydraulic press cylinder.

Referring to the drawing the decompression valve has an actuatingspindle 1 and a mushroom head 2 and it is mounted for relative movementconcentrically in the head of a prefill-exhaust valve 3, which latter isseated in the end of the press cylinder at 4.

The decompression valve head 2 is surrounded by a cylindrical shroud 5forming, in the drawing, an integral extension on the underside of theprefill-exhaust valve 3. The shroud 5 is perforated with a large numberof radial passages 6, of any convenient cross section which in theillustrated example are arranged on a helix. Thus as the valve head 2 ismoved downwards, looking at the drawing, the radial passages 6 areuncovered consecu United States Patent 0 i 2,904,074 Patented Sept. 15,1959 ice tively andthe compressed liquid in the press cylinder hasaccess through ports 7 in the prefill-exhaust valve 3 to the interior ofthe prefill tank 8 to a gradually increasing extent with the object ofreleasing the compressed energy of the liquid at a controlled rate.

A similar eflect may be obtained by disposing the radial passages 6 in aseries of rows one below the other so that asthe decompression valvehead 2 opens it uncovers each row of passages in turn.

In the example illustrated the decompression valve is opened against thepressure in the press cylinder by hydraulic pressure acting against anenlarged ram head 9 the area of which is greater than the area of thevalve 2 which is exposed to the pressure within the press cylinder. Theenlarged head 9 works in a cylinder 10 and co-acts with the inner end ofthe actuating spindle 1 of the decompression valve through a ram 11. Thereturn or closing movement of the decompression valve is effected by aspring 12.

It will be understood that the embodiment illustrated is designed for adownstroking press and therefore both the prefill-exhaust valve and thedecompression valve are opened by being moved downwards into the presscylinder. However, such valves may be mounted horizontally for a pressram and cylinder acting horizontally or vertically upward for thecylinder of an upstroking press without departing from the invention.

What is claimed is:

1. A prefill and exhaust valve mechanism for controlling fluid flow in ahydraulic system comprising, in combination, a prefill and exhaust valvemember movable between open and closed positions, said valve memberhaving a bore with a port opening from the bore to the exhaust side ofthe member and a series of passages opening from the bore to itspressure side of the member, and an auxiliary valve member reciprocablein the bore of said exhaust valve member to initially open said port andthen establish communication between the port and said passages insuccession to permit exhaust of compressed fluid at a controlled rateeffective to avoid a pressure surge.

2. A valve mechanism as defined in claim 1 in which the auxiliary valvemember is a mushroom-type valve and in which the series of passagescontrolled by the auxiliary valve open radially through a shroud formedon the exhaust valve member around the head of the auxiliary valvemember.

3. A valve mechanism as defined in claim 2 in which the radial passagesare arranged in a helix so as to be uncovered consecutively as theauxiliary valve moves toward open position.

4. A valve mechanism for controlling fluid flow in a. hydraulic systemcomprising, in combination, a prefill and exhaust valve member movablebetween open and closed positions, said valve member having a boreopening to both its pressure and exhaust sides, a decompression valvemember reciprocable in said bore operative in one position to close thebore, an integral extension on the pressure side of said exhaust valvemember having a series of passages opening therethrough outwardly fromthe bore at the pressure side of the valve member, said decompressionvalve member being operative in its movement from closed positions toopen said passages successively to said bore to permit a gradual releaseof pressurized fluid and thereby avoid excessive shock or pressuresurge.

5. A valve mechanism as defined in claim 4 including a pressure fluidoperated actuator for moving the decompression valve member from closedtoward open position.

6. A prefill and exhaust valve comprising, in combination, meansdefining a valve port, a main valve member movable relative to said portbetween open and closed fashions, said valve member having an exhaustpassage 7 in-commtmication with an exhaust port at its low pressure sideand with a series of restricted passages at its high pressure side, andan auxiliary valve member Ieciprocable *in-thepassage -insaid main-valvemember from aposition clp'sing saidexhaust port to a position efiectiveto establ'ish communicationbetween said exhaust port and said redrietedpassages in succession.

- Relentless Cited the file of this patent STATES PATENTS Blyston May 7,1929 Ernst Dec. 27, 1933 Cannon Jan. 16, 1940 Cones July 31, 1945 BrehmOct. 24, 1950 v Nowak Dec. 23, 1952 FOREIGN PATENTS Sweden Nov. 13, 1897

